Centrifugal drums



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OOOOOOOOOOOOOOOO DDDDDDDOOOODDD OOOOOOOOOOOOOOOO7 United States Patent O 6 claims. (ci. 21o-ssn) This invention relates to a centrifugal drum With a solid casing for the separation of solid materials from liquid, for example of sugar crystals from sugar filling compositions, the casing of which is provided internally with a sieve.

In the case of large centrifugal drums it is diicult to achieve a uniform distribution of the filling mass applied to the drum wall. With known centrifugal drums the inner wall extends from the cover to the base at the same diameter. With centrifuged material, this construc-V tion leads to unfavourable swellings. These swellings, on the one hand, assist the pendulum motion of the centrifugal drum but on the other hand the centrifuging is irregular. Similarly, the washing of the centrifuged material in the centrifugal drum is made difficult thereby. These disadvantages are removed in accordance with the present invention by the feature that the centre part of the centrifugal drum in the delivery area of the centrifuged material has a smaller inner diameter than its axial end portions, and outlets for the centrifuged liquid are provided only in the bottom and cover of the centrifugal drum. This achieves the advantage that the swellings impeding a uniform centrifugal action are prevented from occurring on the centrifuged material so that, de-

spite a greater .depth of drum, no loss of throughput through the centrifugal drum occurs.

In a preferred embodiment of the invention the axial end portions of the drum casing are hollowed out in the form of rings on their inner side and the hollowed out annular spaces are filled with additional lower sieves. By this means the difference in the inner diameters on the centre portion and the axial end portions of the centrifugal drum can be accommodated in a simple manner. In another embodiment of the centrifugal drum a drum casing having a constant inner diameter is provided in the region of the delivery area of the centrifuged material with a ring reducing the inner diameter of the centrifugal drum at this point. This embodiment is particularly suitable for the subsequent arrangement of already existing centrifugal drums.

A further improvement is achieved in accordance with the invention by the feature that the outlets in the cover and bottom of the centrifugal drum and the outflow means for the liquid are located along the inner Wall of the drum in alignment. By this means, the centrifuging of the liquid is facilitated because changes in the direction of the liquid are avoided.

In the accompanying :drawings two embodiments of the invention are illustrated in which:

FIG. 1 shows an axial cross section 0f a large centrifugal drum,

FIG. 2 is an axial section through the drum of FIG. l on an enlarged scale, and

FIG. 3 is an axial fragmentary section through a second embodiment.

The embodiment shown in FIGS. 1. and 2 has a drum casing 1, a cover 2, a base 3 and a hub 4. The base 3 3,334,751 Patented Aug. 8, 1967 is screwed onto a flange 5 of the hub by screws 6. On the inner wall of the drum casing 1 is a lower sieve 7 which is closed by a cover sieve 8 on the inside. Two axial end portions 9 and 10 of the drum casing 1 are hollowed out in the form of rings. The hollowed out annular spaces 11 and 12 are lled with additional lower sieves 13 and 14. The sieves 7, 8, 13 and 14 are secured by coupling rings 15 in their position on the inner wall of the drum. The centre portion 16 of the Idrum casing has a smaller diameter than the axial end portions 9 and 10. The cover 2 is provided with outlet openings 17 and the base 3 with outlet openings 18 for the centrifuged liquid. The openings 17 and 18 are in alignment with the annular spaces 11 and 12. The delivery zone for the centrifuged material coincides with the centre portion 16 of the drum casing 1. The centrifuged material reaching this area ows upwardly and downwardly uniformly, bulges being avoided by the fact that the centrifuged liquid in the area of the delivery zone cannot flow outwardly through the fdrum wall. The discharge of the liquid along the inner wall of the drum is thereby prevented with the result that the delivered centrifuged material on the cover sieve 8 retains suiiicient liquid to prevent bulging. At the points 19 and 20 of the axial end portions 9 and 10 the liquid experiences a greater centrifugal speed on account of the larger diameter of the ydrum casing 1 beginning at these points. Thus disintegration of the previously existing blockage and accelerated discharge of the liquid begins at the ends of the centrifugal drum so that if a suicient impediment to the uid is maintained in the delivery areas 16, a faster throughput is achieved.

In the embodiment shown in FIG. 3 the reduction of the inner diameter of the centre portion of the drum is achieved by the feature that a ring 22 is inserted in the drum casing 21 having a constant inner diameter and it will be appreciated that this ring can also be introduced subsequently to manufacture of the drum. Moreover, this embodiment is constructed exactly as the embodiment shown in FIGS. 1 and 2.

What we claim is:

1. A centrifugal drum for the separation of solid material from liquids comprising an imperforate axially rotatable casing with centre and axial end portions, a base and a cover, a sieve tting being carried internally of the casing over said centre and axial end portions, internal hollow rings in the form of recessed annular spaces defined by said axial end portions, additional lower sieves provided in said recessed annular spaces and outlet openings from the casing for outlet of separated liquid being provided only at the base and the cover, said recessed annular spaces and said outlet openings being in alignment and in communication with one another.

2. A centrifugal drum as claimed in claim 1 in which said' centre and axial end portions are of unitary construction.

3. A centrifugal drum for separating a solid fraction from a liquid, comprising, in combination, an imperforate rotatable casing having axial end portions and a center portion of a lesser diameter than the diameter of said axial end portions; a base member and a cover member respectively associated with one of said end portions; a sieve fitting received within said casing and deiining with said end portions a pair of annular spaces wherein the liquid is subjected to acceleration due to undergoing increased centrifugal force because of the larger diameter of said end portions; sieve elements received in to said casing immovably relative thereto.

, 3 4 the respective annularspaces; and outlet means for sepa- References Cited rated liquid Qrovided in at least one of said members. UNITED STATES PATENTS 4. A centrifugal drum as claimed 1n claim 3, Whereln said sieve elements are of annular configuration. 959173 5/1910 shapley 21o-380 X 5. A centrifugal :drum as claimed in claim 3; and fur- 5 1770854 7/1930 Johnson 21o-380 ther comprising means for securing said sieve elements 119461500 2/1934 Roberts 21o-380 2,312,829 3/1943 Blrd et al, 210-380 X 6. A centrifugal drum as claimed in claim '3, wherein said annular spaces and said outlet means communicate REUBEN FRIEDMAN Primary Exammer" with one another and are in alignment. l0 I. L. DE CESARE, Assistant Examiner 

1. A CENTRIFUGAL DRUM FOR THE SEPARATION OF SOLID MATERIAL FROM LIQUIDS COMPRISING AN IMPERFORATE AXIALLY ROTATABLE CASING WITH CENTRE AND AXIAL END PORTIONS, A BASE AND A COVER, A SIEVE FITTING BEING CARRIED INTERNALLY OF THE CASING OVER SAID CENTRE AND AXIAL END PORTIONS, INTERNAL HOLLOW RINGS IN THE FORM OF RECESSED ANNULAR SPACES DEFINED BY SAID AXIAL END PORTIONS, ADDITIONAL LOWER SIEVES 